Infective Endocarditis
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Introduction
- A microbial infection of the endocardium and diseased heart valves (rheumatic heart disease, congenital heart disease, shunts, and prosthetic valves).
- May be acute or sub-acute
- Some acute cases occur in normal valves in intravenous drug users or may be part of systemic illness
- Sub-acute form usually occurs on diseased valves
- Causative organisms include: Streptococci, Staphylococci, Enterococci; Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella species ('Hacek' Organisms)
Clinical features
Acute:
- High fever with rigors
- Delirium
- Shock
- Development of new murmurs
- Severe cardiac failure
- Abscesses may form in many parts of the body (e.g. brain)
Subacute:
- Low-grade fever
- Signs of carditis
- Finger clubbing
- Arthralgia
- Splenonegaly
- Osler's nodules
- Janeway lesions
- Roth spots
Differential diagnoses
- Myocarditis
- Rheumatic heart disease
Complications
- Cardiac failure
- Destruction of heart valves
- Systemic embolism (could be infective)
Investigations
- Full Blood Count and differentials; ESR
- Urinalysis; urine microscopy
- Blood cultures X 3 (the yield is higher at the time of pyrexia)
- Chest radiography
- ECG
- Echocardiography
Treatment goals
- Stop the infection
- Treat cardiac failure
- Prevent coagulation disorders
Non-drug treatment
- Bed rest
- Low salt diet
Drug treatment
Initiate therapy (culture results awaited) with:
- Benzylpenicillin 7.2 g daily by slow intravenous injection or intravenous infusion in 6 divided doses for 4 -6 weeks
- May be increased up to 14.4 g daily if necessary (e.g. in endocarditis)
Plus:
- Gentamicin 60 - 80 mg intravenously 12 hourly for 2 weeks
Following bacteriological confirmation institute appropriate antimicrobial therapy
Staphylococci:
- Flucloxacillin: 250 mg - 2 g intravenously every 6 hours for 4 - 6 weeks
- Vancomycin: 1 gm intravenously 12 hourly; Gentamicin 60-80 mg intravenously 12 hourly for 2 weeks
Enterococci:
Amoxicillin 2 gm intravenously 4 hourly; intravenously Gentamicin 60-80 mg 12 hourly
Candida:
Systemic antifungals
- Amphotericin B: 8 - 1 mg/kg/day IV for at least 6 weeks
Plus
- Flucytocine: 25 mg/kg/day in 6 hourly
Notable adverse drug reactions, contraindications and caution
- Penicillin: rashes, anaphylaxis
- Gentamicin: nephropathy
- Monitor patients on gentamicin and vancomycin carefully
Prevention
Prophylactic antibiotics for patients at risk who are undergoing:
Dental procedures. Under local or no anaesthesia, for those who have NOT had endocarditis, and have NOT received more than a single dose of penicillin in the last one month:
Amoxicillin
Adult: 3g orally 1 hour before procedure
Child under 5 years: 750 mg orally 1 hour before procedure;
5- 10 years: 1.5 g
For penicillin-allergic patients or patients who have received more than a single dose of a penicillin in the previous one month:
Azithromycin
Adult: 500 mg orally one hour before procedure
Child under 5 years: 200 mg orally;
5 - 10 years: 300 mg
Patients who have had endocarditis:
Amoxicillin plus gentamicin intravenously as for procedures under general anaesthesia (see below)
Dental procedures under general anaesthesia, and no special risk:
Amoxicillin
Adult: 1 g intravenously at induction of anaesthesia; additional dose orally 6 hours later
Child under 5 years: a quarter of adult dose;
5 - 10 years half adult dose
Or:
Adult: 3g orally 4 hours before induction, then 3g as soon as possible after the procedure
Child under 5 years: a quarter of adult dose;
5 – 10 years old half adult dose
Special risk, e.g. previous infective endocarditis, or patients with prosthetic valves:
Amoxicillin plus gentamicin intravenously
Adult: 1 g amoxicillin plus 120 mg gentamicin at induction
Then oral amoxicillin 500 mg 6 hours after procedure
Child under 5 years: a quarter of adult dose
plus 2 mg/kg gentamicin intravenously at induction
5 - 10 years: half adult dose for amoxicillin; 2 mg/kg gentamicin
Patients who are penicillin-allergic or have received more than a single dose of a penicillin in the last one month:
Vancomycin
Adult: 1g intravenously over at least 100minutes
Child under 10 years: Vancomycin 20 mg/kg
Plus
Gentamicin
Adult: 120 mg intravenously - Given at induction or 15 minutes before procedure
Child under 10 years: Gentamicin 2 mg/kg
Genito-urinary tract manipulation
As for special risk patients undergoing dental procedures under general anaesthesia
Obstetrics, gynaecological and gastrointestinal procedures
As for genitourinary tract manipulation